<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>浮动练习</title>
        <style>
            *{
                margin:0;
                padding: 0;
            }
            div{
                width: 612px;
                height: 182px;
                position: absolute;
                top:0;left:0;
                right:0;bottom:0;
                margin: auto;
                border: 1px solid black;
            }
            ul li{
                width: 100px;
                height: 88px;
                float: left;
                text-align: center;
                line-height: 88px;
                list-style: none;
                border-right: 1px solid black;
                border-top: 1px solid black;
                border-bottom: 1px solid black;
                background-color: #6d91cf;
            }
            li:hover{
                background-color: #3064bb;
            }
            ul li:nth-child(1),ul li:nth-child(2){
                width: 200px;
            }
        </style>
    </head>
    <body>
        <div>
            <ul>
                <li>维护人民健康</li>
                <li>《求是》发表习近平重要文</li>
                <li>九一八89周年</li>
                <li>最冷早晨将至</li>
                <li>留学回国人员</li>
                <li>国庆中秋</li>
                <li>上海新增</li>
                <li>少林寺回应</li>
                <li>进口冻带鱼</li>
                <li>美国山火</li>
            </ul>
        </div>
    </body>
</html>